Estimation of Simultaneous Occurrence Frequency and Damage Risk in Main and Tributary River Basins Considering Inland and River Flooding Under Climate Change

Key Points

• This research aims to evaluate the frequency of simultaneous flooding occurrences and their associated damage risks in river basins affected by climate change.
• Utilized 5km resolution warming prediction data
• Analyzed past occurrences of simultaneous river stage and peak rainfall in tributary basins
• Conducted flood analysis to estimate financial damage from flooding
• Assessed damage risk based on simultaneous inland and river flooding occurrences
• Identified only one past case of simultaneous flooding events between the main and tributary rivers
• Simultaneous flooding frequency increases with a 4°C rise in temperature
• Estimated over 5000 properties impacted by inland flooding even under peak conditions
• Combined flooding leads to approximately twice the damage compared to inland flooding alone